fix(desktop): incorrect titlecase in mail subject

[Nixieboluo]

【sealos】Verification Code

【Sealos】Verification Code

[gru-agent]

TestGru Assignment

Summary

Link	CommitId	Status	Reason
Detail	e395cb3	🚫 Skipped	No files need to be tested {"frontend/desktop/src/services/backend/sms.ts":"File path does not match include patterns."}

History Assignment

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